1. Field of the Invention
The present invention relates to railroad passenger cars generally and, more particularly, but not by way of limitation, to a novel disaster lighting system for railroad passenger cars.
2. Background Art
Railroad passenger cars typically have both normal and emergency lighting systems. Emergency lighting power for each railroad car is provided by a central battery in the car and also an internal battery emergency ballast, both charged from a 60 Hz power source provided from the locomotive. When cars are not in service, they are stored at night and over the weekend without AC power. Unless proper steps are taken to disable the emergency lighting system, the emergency lighting system senses the loss of AC power and provides emergency lighting with incandescent lamps or fluorescent lamps with inverter ballast from the central battery until AC power is restored or the battery is totally discharged. Total discharge can occur from 8 to 12 hours, depending on the emergency load and battery condition. Lights equipped with internal battery emergency ballast are normally inhibited with a voltage sensitive relay from coming ON until the central battery voltage drops to between 15 and 30 volts. At this point, the internal battery emergency ballast provides lighting for up to 120 minutes, totally discharging the nickel cadmium emergency battery. Essentially, each day or over each weekend the internal emergency battery is discharged.
When AC power is restored, the central battery is charged from its charger and the emergency battery is charged at a trickle charge at five percent of its rated Ampere-hour capacity and requires 24 hours for full Ampere-hour capacity. A major problem with this scheme is that, should a disaster occur before the emergency battery is fully charged, the emergency battery pack would not provide the illumination for the required 90 minutes. In addition, the life of the emergency battery pack is based on 500 charge/discharge cycles. In conventional systems, the loss of AC power is so frequent that the battery life is only two years compared with building applications where a five- to seven-year life is normal.
The requirement for 90 minutes of emergency lighting is given in Federal Register, Vol. 64, No. 91, Wed. May 12, 1999, paragraph 238.115, pp. 25596-25598; NFPA 101, 2000 Edition, xe2x80x9cLife Safety Codexe2x80x9d, paragraph 7.9.3, xe2x80x9cPeriodic Testing of Emergency Lighting Equipmentxe2x80x9d, and APTA RP-E-013-99, xe2x80x9cStandard For Emergency Lighting Systems Design for Passenger Carsxe2x80x9d.
xe2x80x9cDisasterxe2x80x9d as used herein means a situation in which normal AC power is interrupted and DC power is interrupted or the voltage thereof drops below a predetermined level. Such a disaster could occur, for example, if there is a wreck or other unusual situation in which power is lost.
Accordingly, it is a principal object of the present invention to provide a disaster lighting system for railroad passenger cars that will provide assurance that the disaster battery will not be discharged by the normal lay-up procedures of the railroad.
It is a further object of the invention to provide such a disaster lighting system that will provide lighting in the event AC power is interrupted and DC power is interrupted or drops below a predetermined voltage level.
It is an additional object of the invention to provide such disaster lighting for a period of at least 90 minutes.
It is another object of the invention to provide such a disaster lighting system that can operate for a period of at least 90 minutes even if normal AC and DC and DC emergency power is lost.
It is yet a further object of the invention to provide such a system that can be economically implemented.
It is yet an additional object of the invention to provide such a disaster lighting system that can be retrofitted to existing railroad passenger cars.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.
The present invention achieves the above objects, among others, by providing, in a preferred embodiment, a disaster lighting system for a railroad passenger car of the type in which emergency lighting is provided for a first predetermined length of time if AC power is lost, comprising: a first sensor operatively connected to detect loss of AC power to said railroad passenger car and to provide a first output indicative thereof, a second sensor to detect loss of DC power from a central battery in said railroad passenger car or lowering of voltage thereof below a predetermined level and to provide a second output indicative thereof, and a controller operatively connected to receive said first and second outputs and to initiate disaster lighting for a second predetermined length of time if said AC power is lost and if said DC power is lost or voltage of said DC power drops below said predetermined level.